Gangs are opting to sell methamphetamine instead of cannabis in small towns and rural areas to generate more cash.

The new research comes from the study, Determinants of High Availability of Methamphetamine, Cannabis, LSD and Ecstasy in New Zealand, was at the APSAD Scientific Alcohol and Drug Conference, where leading researchers, clinicians, policy makers and community representatives from across Australasia are gathered to share latest insights into major alcohol and other drug issues facing society.

"Many small towns in New Zealand have reported very high availability of methamphetamine, and conversely, a shortage of cannabis," lead researcher Associate Professor Chris Wilkins, from Massey University's SHORE & Whāriki Research Centre, said.

"Local commentators have suggested drug dealers are deliberately promoting methamphetamine at the expense of cannabis. Our study sought to investigate this."

The study revealed methamphetamine was more available than cannabis in all areas, and more available in rural areas and small towns than cities.

Cannabis availability was notably low in places where methamphetamine availability was particularly high, Wilkins said.

"These findings suggest that it may be the case that gangs are able to gain monopoly control over drugs markets in small towns and promote methamphetamine in favour of cannabis to maximise revenue.

"We need further research to understand these relationships," said Wilkins. "It may be the case that small towns offer an environment where a gang can control the local drugs market."